When a witness is being cross-examined, it is generally considered fair game to attempt to impeach or discredit the witness by asking about any criminal convictions. Section 491.050, RSMo provides in relevant part:
“any prior criminal convictions may be proved to affect [witness] credibility in a civil or criminal case and, further, any prior pleas of guilty, pleas of nolo contendere, and findings of guilty may be proved to affect [witness] credibility in a criminal case. Such proof may be either by the record or by his [or her] own cross-examination, upon which he [or she] must answer any question relevant to that inquiry”
Additionally, the Missouri Supreme Court has found that it is universally acceptable to cross-examine a witness about prior convictions even though the convictions do not involve similar facts. The reason for this is that the witnesses credibility is in issue and may be impaired by prior criminal convictions. As a result, it is important to discuss any past criminal convictions when preparing for testimony and cross-examination.